Chironomus tentans life-cycle test: design and evaluation for use in assessing toxicity of contaminated sediments

• Published in: Environmental toxicology and chemistry 1997-06, Vol.16 (6), p.1165-1176
• Main Authors: Benoit, D.A. (U.S. Environmental Protection Agency, Duluth, MN.), Sibley, P.K, Juenemann, J.L, Ankley, G.T
• Format: Article
• Language: English
• Subjects: Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; CHIRONOMUS; Chironomus tentans; Ecotoxicology, biological effects of pollution; Effects of pollution and side effects of pesticides on protozoa and invertebrates; Freshwater; Fundamental and applied biological sciences. Psychology; Life-cycle test; POLLUTION DE L'EAU; POLUCION DEL AGUA; SEDIMENT; Sediment toxicity assessment; SEDIMENTO; TOXICIDAD; TOXICITE
• ISSN: 0730-7268; 1552-8618
• DOI: 10.1002/etc.5620160611

The development and standardization of toxicity test methods for assessing toxicity of contaminated freshwater sediments has focused predominantly on short-term exposures and lethality. In many situations, however, toxicity is more likely to become manifest over long periods of time so there is need for standardized testing procedures by which sublethal sediment toxicity can be adequately assessed. In this study, we present and evaluate a new life cycle test, using the midge Chironomus tentans, which enables the assessment of sublethal toxicity of contaminated sediments. In designing the life cycle test, our goal was to make the assay relatively straightforward and, to the extent possible, methodologically compatible with the standard 10-d test. The test is initiated with newly hatched ( 24 h) larvae and uses four effects-based endpoints to assess toxicity: survival, growth, emergence, and reproduction. Survival is determined at 20 d and at the end of the test by back-calculating through emergence data. Growth can be determined at 20 d, which corresponds to the 10-d endpoint in the 10-d C. tentans growth test initiated with 10-d-old larvae. From day 23 to the end of the test, emergence and reproduction are monitored daily. The number of eggs per female is determined for each egg mass, which is then incubated for 6 d to determine hatching success. Each treatment in the life cycle test is terminated separately after 7 consecutive days without emergence. We evaluated the life cycle test by following one generation of C. tentans in sediments collected from the upper Mississippi River. Survival of larvae exceeded 90% at 20 d. Of these larvae, between 60 and 70% successfully emerged: survivorship among pupae and adults exceeded 85%. Mean egg production ranged from 906 to 1,107 eggs per female. The test required 65 d to complete, including pretest preparation. These data show that the C. tentans life cycle test can be used to assess sublethal toxicity accurately in contam